1. Field of the Invention
The present invention relates to a high-speed switching router using an APS (Automatic Protection Switching) and a high-speed switching method of a communication line in the same.
2. Description of the Related Art
A conventional high-speed switching router using an APS has a POS (Packet over SONET/SDH) interface. There are two conventional methods in a fault avoidance routing function using APS (1+1) method in SONET (Synchronous Optical Network)/SDH (Synchronous Digital Hierarchy) in the conventional router. That is, in one conventional method, the ASP is operated by combining two routers as shown in FIG. 1, and in the other conventional method, the APS is operated in one router as shown in FIGS. 2A and 2B.
In conjunction with the above description, Japanese Laid Open Patent Application (JP-A-Heisei 11-331170) is known as a first conventional example. In this first conventional example, a current use system link and a stand-by system link for the backup of the current use system link are provided, and optical transmitter and receiver and an optical cable are duplicated in an ATM interface card. With this structure, only a physical link is duplicated and is connected with an ATM switch.
In the above structure, when an ATM cell is received, whether the ATM cell is received via a current use system ATM switch or a stand-by system ATM switch is checked. When it is determined that the ATM cell is received via the stand-by system link, serial data received by an optical receiver is returned by a selecting section not to receive the ATM cell. The first conventional example says that the duplication of the ATM interface card is unnecessary, resulting in reduction of cost of the apparatus.
However, the above conventional IP router with the line fault avoidance routing function using the APS in SONET/SDH, a 2-link PPP (Point to Point Protocol) is used. The switching using the APS in the SONET/SDH is carried out as an fault avoidance routing operation of an ordinary rate in the IP router. Therefore, the high-speed switching in the SONET/SDH is not utilized sufficiently.
The PPP link in the POS is used for every one physical interface in the above two conventional methods. In case of the APS (1+1) method, the two PPP links exist. For this reason, because an IP address on the router ground side is changed in the APS switching on fault detection, IPCP (Internet Protocol Control Protocol) of the PPP needs re-negotiation. Also, the routing re-calculation is necessary because of the address change. Therefore, it takes a long time until IP Packets can be transmitted once again after APS switching.
Also, a communication path duplication control system is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 4-58636). In this conventional example, the system is composed of a communication control section which switches between two communication paths. A communication monitoring section monitors the communication paths. Management data is provided to manage each of the communication paths between two transmission apparatuses in units of transmission apparatuses. The two transmission apparatuses are shared by the communication control section and the communication monitoring section. When a current communication state is different from that shown by the management data, the management data is updated by the communication control section or the communication monitoring section. Then, the path is switched in units of transmission apparatuses based on the updated management data.
Also, a line switching control system is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 7-226729). In this conventional example, an inserting section is provided for each of transmission units to insert fault data in main signals on a current use path and a stand-by path. The fault data shows the existence or non-existence of a fault in a transmission section of each transmission unit. An extracting section of the transmission unit extracts the fault data. A selection section of the transmission unit selects one of the current use path and stand-by path, which is not related with the fault, based on the extracted fault data, and extracts switching control data from the selected path.
Also, an APS system of an ATM switching network is disclosed in Japanese Laid Open Patent Application (JP-A-Heisei 9-74412). In this conventional example, first and second units are connected by a working line and a protection line. Each of the first and second units is composed of a bridge section, a switch and a control section. The bridge section bridges the working line and the protection line on a transmission side. The switch selects one of the working line and the protection line on a receiving side. The control section generates K byte data for realizing APS, receives the K byte data from the protection line, analyzes the K byte data. The control section adds predetermined data to the K byte data and controls the switch to carry out the switching operation.